The present invention relates to a method for preparing a kit part used for a bleach-fixing solution and a kit used for a bleaching solution for silver halide color photographic light sensitive materials and a method for processing silver halide color photographic light sensitive materials by the use thereof.
The method for obtaining color photographic images is commonly comprised of a process of forming dye images obtained through color development and a process of removing metallic silver formed together with the dye images from a silver halide color photographic material, a so-called desilvering process. The desilvering process is a step of processing a developed silver halide color photographic material with a bleaching solution containing halide ions and an oxidizing agent to cause formed metallic silver to be changed to silver halide, followed by processing with a fixing solution containing a silver halide solvent to remove the silver halide formed by bleaching as well as any remaining unexposed and undeveloped silver halide. There is also known a process of conducting bleaching and fixing in a single solution, a so-called bleach-fixing solution.
Potassium hexacyanoferrate (III), so-called red prussiate and ferric chloride have been hitherto employed as a bleaching agent. However, the use thereof has been limited in view of environmental concern and corrosion of equipments, and at present, (ethylenediaminetetraacetato)iron (III) complex and (1,3-propylenediaminettraacetato)iron (III) complex are broadly employed from the viewpoint of bleaching ability and economic reasons. However, (ethylenediaminetetraacetato)iron (III) complex and (1,3-propylenediaminettraacetato)iron (III) complex are difficult to initiate microbiological degradation and the use thereof produces problems from the point of view of global environmental protection. Recently, specifically in German, studies of a rule for limiting discharge of hardly degradable chelating agents to rivers and drains have been made, so that there is desired development of a photographic bleaching agent to overcome such problems.
In such a situation, development of biodegradable bleaching agents was made, including, for example, a technique of using iron (III) complexes of monoaminoalkylcarboxylic acid derivatives described in JP-A No. 7-181655 (hereinafter, the term, JP-A refers to Japanese Patent Application published for public inspection) and a technique of using alkylenediamine-N,Nxe2x80x2-disuccinic acid iron (III) complex salts as a bleaching agent, as described in JP-A Nos. 4-313752 and 5-72695. However, it was proved that the foregoing iron (III) complexes of monoaminoalkylcarboxylic acid derivatives were insufficient in bleaching ability and the use of alkylenediamine-N,Nxe2x80x2-disuccinic acid iron (III) complex salts produced difficulties with respect to their costs and stability.
To overcome such problems was proposed a technique, in which alkylenediamine-N,Nxe2x80x2-disuccinic acid was made to react with (A) ammonia or an alkali metal hydroxide and (B) iron hydroxide in an aqueous solution, followed by oxidation of the reaction product, as described in JP-A No. 7-291984; a method of preparing an aminopolycarboxylic acid iron (III) complex, in which a peroxo-compound was added to an aqueous solution containing an aminopolycarboxylic acid iron (II) complex and ammonia to cause oxidation thereof, as described in JP-A 7-2745; and a method of ethylenediamine-N,Nxe2x80x2-disuccinic acid meso-form iron (III) complex, in which triiron tetraoxide was added to an isomer mixture of a meso form and a racemic form of ethylenediamine-N,Nxe2x80x2-disuccinic acid to cause to perform a heating reaction. However, such proposals were still insufficient. For example, oxidation by using air or a peroxo-compound or heating reaction during the preparation process caused decomposition of alkylenediamine-N,Nxe2x80x2-disuccinic acid to produce impurities, producing problems in that precipitates were formed or the silver-bleaching ability of a silver halide photographic material was adversely affected, so that new technical developments are still being sought.
Accordingly, it is a first object of the present invention to provide a method for preparing a kit part of a bleach-fixing solution and a bleaching solution for use in silver halide color photographic materials, with minimized impurities and without adversely affecting photographic performance, and a method of processing a silver halide color photographic material by the use thereof.
It is a second object of the invention to provide a method for preparing a kit part of a bleach-fixing solution and a bleaching solution for use in silver halide color photographic materials, without forming precipitates or crystals after aging, while exhibiting superior storage stability, and a method of processing a silver halide color photographic material by the use thereof.
It is a third object of the invention to provide a method for preparing a kit part of a bleach-fixing solution and a bleaching solution for use in silver halide color photographic materials, resulting in an enhanced yield and exhibiting superior economic feasibility, and a method of processing a silver halide color photographic material by the use thereof.
The foregoing objects of the invention were accomplished by the following constitution:
1. A method for preparing a kit part of a bleach-fixing solution for use in silver halide color photographic materials, the method comprising the steps of:
adding a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt into a mixing tank to form a solution thereof, and then
adding thereto at least one iron (III) salt selected from the group consisting of iron (III) nitrate, iron (III) chloride, iron (III) bromide, (M1)3Fe(SO4)3 and M1Fe(SO4)2, in which M1 represents an ammonium, potassium, sodium or hydrogen atom, while maintaining the solution at 35 to 80xc2x0 C.; and
2. A method for preparing a kit of a bleaching solution for use in silver halide color photographic materials, the method comprising the steps of:
adding a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt into a mixing tank to form a solution thereof, and then
adding thereto at least one iron (III) salt selected from the group consisting of iron (III) nitrate, iron (III), chloride, iron (III) bromide, (M1)3Fe(SO4)3 and M1Fe(SO4)2, in which M1 represents an ammonium, potassium, sodium or hydrogen atom, while maintaining the solution at 35 to 80xc2x0 C.
Furthermore, preferred embodiments of the invention are as follows:
3. The method as described in 1 or 2 above, wherein the solution added with the [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt into a mixing tank exhibits a pH of 6 to 10;
4. The method as described in 1, 2 or 3 above, wherein the kit part of a bleach-fixing solution or the kit of a bleaching solution each exhibit a pH of 3.5 to 6.0;
5. The method as described in any of 1 through 4 above, wherein the kit part of a bleach-fixing solution or the kit of a bleaching solution contains a compound represented by the following formula (1):
MOOCxe2x80x94(Z)kxe2x80x94(X)nxe2x80x83xe2x80x83formula (1) 
xe2x80x83wherein X represents xe2x80x94COOM2, xe2x80x94OH, xe2x80x94SO3M3 or xe2x80x94PO3M4M5; M, and M2 through M5 each represent an alkali metal or a hydrogen atom; n is an integer of 1 to 3, provided that when n is 2 or more, plural Xs may be the same or different; Z represents a (n+1)-valent linking group having 1 to 10 carbon atoms and comprising carbon(s) and hydrogen atom(s), or carbon atom(s), hydrogen atom(s) and oxygen atom(s); and k is 0 or 1;
6. The method as described in any of 1 through 5 above, wherein the kit part of a bleach-fixing solution or the kit of a bleaching solution contains an alkylenediamine-N-monosuccinic acid or its salt;
7. The method as described in any of 1 through 6 above, wherein after adding the iron (III) salt, stirring is performed in the mixing tank by propeller stirring or circulation stirring, wherein the propeller stirring is performed using a rotary blade having a turning radius of not less than xc2xc of the radius of the mixing tank at a stirring rate of 50 to 120 r.p.m, and the circulation stirring being performed at a circulation rate of 2.0 to 5.5 cycles/min;
8. The method as described in any of 1 through 7 above, wherein the molar ratio of the [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt to the iron (III) salt is 1.00 to 1.10;
9. A method of processing a silver halide color photographic material by the use of a kit part of a bleach-fixing solution prepared by the method as described in 1 or any of 3 through 8 above, or by the use of a kit of a bleaching solution prepared by the method as described in 2 or 3 through 8 above.
In the method for preparing a kit part of a bleach-fixing solution for use in silver halide color photographic materials (hereinafter, also denoted as a kit part of a bleach-fixing solution relating to the invention) or a kit of a bleaching solution for use in silver halide color photographic materials (hereinafter, also denoted as a kit of a bleaching solution relating to the invention), one aspect of the invention concerns the use of a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt.
The [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt relating to the invention is preferably a compound represented by the following formula (A): 
wherein M1, M2, M3 and M4 each represent a hydrogen atom, an alkali metal or a cation such as ammonium; X represents an alkylene group having 2 to 6 carbon atoms, which may be substituted, or xe2x80x94(B1O)nxe2x80x94B2xe2x80x94, in which n is an integer of 1 to 6, B1 and B2 which may be the same or different are each an alkylene group having 1 to 5 carbon atoms; R1 and R2 each represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
Preferred examples of [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt used in the invention are shown below, but the invention are by no means limited to these. 
Any of the foregoing compounds is a [S,S]-isomer (optical isomer). Of these, compounds (A-1), (A-3) and (A-12) are preferred. The foregoing exemplified compounds are each represented by an acidic form but their salts (such as ammonium, potassium or sodium salts) are also usable in the invention.
In the method for preparing a kit part of a bleach-fixing solution or a kit of a bleaching solution, another aspect of the invention concerns the use of at least one iron (III) salt [hereinafter, also referred to as a ferric salt] selected from the group consisting of iron (III) nitrate (or ferric nitrate), iron (III) chloride (or ferric chloride), iron (III) bromide (or ferric bromide), and compounds represented by general formulas of 3M1.Fe(III) (SO4)3 and M1.Fe(III) (SO4)2, in which M1 represents an ammonium, potassium, sodium or hydrogen atom. As an iron (III) salt relating to the invention can be used a compound selected from the iron (III) salts described above and exemplary examples thereof include iron (III) nitrate, iron (III) chloride, iron (III) bromide, triammonium iron (III) trisulfate, tripotassium iron (III) trisulfate, trisodium iron (III) trisulfate, potassium iron (III) sulfate, sodium iron (III) sulfate, and ammonium iron (III) sulfate.
In the method for preparing a kit part of a bleach-fixing solution or a kit of a bleaching solution according to the invention, the above-described [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt is added into a mixing tank containing mother liquor (such as water) to form a solution, and at least one of the iron (III) salts described above is further added thereto subsequently.
In one preferred embodiment of the invention, the solution prepared by adding a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt into the mixing tank is adjusted so as to exhibit a pH of 6 to 10. Adjusting the pH of the solution to the foregoing range results in further enhanced effects of the invention. Specifically, the pH is more preferably 7 to 8.5.
In one preferred embodiment of the invention, the pH of a kit part of a bleach-fixing solution and the pH of a kit of a bleaching solution are each within the range of 3.5 to 6.0, thereby achieving further enhanced effects of the invention more suitably. The pH of 4.0 to 5.5 is more preferred.
In one embodiment of the invention, i.e., in the preparation method of a kit part of a bleach-fixing solution or a kit of a bleaching solution, an organic acid represented by the following formula (1) is employed:
xe2x80x83MOOCxe2x80x94(Z)kxe2x80x94(X)nxe2x80x83xe2x80x83formula (1)
wherein X represents xe2x80x94COOM2, xe2x80x94OH, xe2x80x94SO3M3 or xe2x80x94PO3M4M5, in which M2 through M5 each represent an alkali metal or hydrogen atom; n is an integer of 1 to 3, provided that when n is 2 or more, plural Xs may be the same or different; Z represents a (n+1)-valent linking group having 1 to 10 carbon atoms and comprising carbon(s) and hydrogen atom(s), or carbon atom(s), hydrogen atom(s) and oxygen atom(s); and k is 0 or 1; M represents an alkali metal or a hydrogen atom.
Of the organic acids represented by the foregoing formula (1), an organic acid represented by the following formula (1-A) or (1-B) is preferred: 
wherein L8 and L9 are each an alkylene group; r2 and r3 are each 0 or 1; r4 is an integer of 1 to 5; q is an integer of 0 to 4, provided that r4+qxe2x89xa65; and M is an alkali metal or a hydrogen atom;
Xxe2x80x94(Y)r5xe2x80x94COOMxe2x80x83xe2x80x83formula (1-B) 
wherein Y is 
wherein L10 and L11 are each an alkylene group; r5 through r8 are each 0 or 1; A10 and A11 are each xe2x80x94H, xe2x80x94OH, xe2x80x94COOM1, xe2x80x94SO3M2, or xe2x80x94PO3M3M4, in which M and M1 through M4 are each an alkali metal or hydrogen atom.
Of the organic acids represented by the formula (1-B), specifically preferred compounds are those represented by the following formula (1-B1) or (1-B2)
MOOCxe2x80x94(CH2)p6xe2x80x94Xxe2x80x83xe2x80x83formula (1-B1) 
MOOCxe2x80x94(CH2)p7xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)p8xe2x80x94Xxe2x80x83xe2x80x83formula (1-B2) 
wherein p6 is an integer of 0 to 6 and more preferably an integer of 2 to 4; P7 and p8 are each an integer of 0 to 3, and more preferably 0. It is specifically preferred that X be xe2x80x94COOM1, and M and M1 are each an alkali metal or a hydrogen atom.
Exemplary examples of the organic acid represented by formula (1) are shown below, but are by no means limited to these. 
Preferred of the foregoing exemplified compounds are specifically compounds (1-5), (1-6), (1-10), (1-15), (1-21), (1-23) and (1-29). Examples of a salt of the acid described above include an ammonium salt, lithium salt, sodium salt and potassium salt; and sodium and potassium salts are preferable in terms of storage stability. The organic acids described above can be used alone or in combination thereof.
In one preferred embodiment of the invention, an alkylenediamine-N-monosuccinic acid or its salt is employed, thereby the objective effects of the invention can be achieved more suitably. The alkylenediamine-N-monosuccinic acid or its salt used in the invention is preferably a compound represented by the following formula (B): 
wherein M1 and M2 each represent a hydrogen atom, alkali metal atom or a cation such as ammonium; X represents an alkylene group having 2 to 6 carbon atoms, which may be substituted, or xe2x80x94(B1O)nxe2x80x94B2xe2x80x94, in which n is an integer of 1 to 6 and B1 and B2, which may be the same or different, is an alkylene group having 1 to 5 carbon atoms; R2 and R2 are each a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
Preferred examples of the compound represented by the formula (B) are shown below. 
The foregoing exemplified compounds may be a [S,S]-form (optical isomer). Although the foregoing exemplified compounds are represented in the form of a free acid, they may be in the form of a salt of ammonium or any cation (such as sodium, potassium or lithium ion). Preferable of the foregoing compounds is specifically compound (B-1). The alkylenediamine-N-monosuccinic acid or its salt used in the invention is contained preferably in an amount of 0.05 to 2.0 mol/l.
In one preferred embodiment of the invention, the preparation method of a kit part of a bleach-fixing solution or a bleaching solution kit is characterized in that at least after adding the ferric salt, stirring within the mixing tank is carried out by means of propeller stirring or circulation stirring, wherein the propeller stirring is performed using a rotary blade having a turning radius not less than xc2xc of the radius of the mixing tank at a stirring rate of 50 to 120 r.p.m and the circulation stirring being performed at a circulating speed of 2.0 to 5.5 cycles/min, and whereby the intended effects of the invention can be suitably achieved. Further, it is specifically preferred that the rotary blade used in the propeller stirring preferably have a turning radius of {fraction (1/3.5)}to xc2xdof the mixing tank radius and be rotated at a rate of 60 to 100 r.p.m., or the circulation stirring be performed at a circulating speed of 2.5 to 4.5 cycle/min, thereby, the intended effects of the invention can be suitably achieved. Herein the turning radius is a length of from the rotation center to the top of the blade. In cases where the mixing tank is not circular, the radius of the tank is defined as a radius of a circle inscribing the wall of the tank.
Furthermore, after adding a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt into the mixing tank to form a solution, the iron (III) salt of the invention is added to the solution maintained at a temperature of 35 to 80xc2x0 C. (preferably 40 to 70xc2x0 C.). It was proved that precipitation easily occurred at a temperature lower than 35xc2x0 C. during the addition of the iron salt and in the case of a temperature higher than 80xc2x0 C., silver retention occurred at the time of processing.
In one preferred embodiment of the invention, the preparation method of a kit part of a bleach-fixing solution or a bleaching solution kit is characterized in that the molar ratio of a [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid or its salt to an iron (III) salt is 1.00 to 1.10, whereby the intended effects of the invention can suitably be achieved. To more suitably achieve the intended effects of the invention is specifically preferred the molar ratio of 1.00 to 1.05. The [S,S]-alkylenediamine-N,Nxe2x80x2-disuccinic acid (or its salt) and iron (III) salt are each contained preferably in an amount of 0.05 to 2.0 mol/l.
In the kit part of a bleach-fixing solution or in the kit of a bleaching solution relating to the invention, the ammonium content is preferably 0 to 30 mol %, based on total cations contained therein, whereby the intended effects of the invention can be suitably achieved. The ammonium content is more preferably 0 to 10 mol % is, whereby odor is minimized and the intended effects of the invention can be more suitably achieved.
The kit part of a bleach-fixing solution or the bleaching solution kit relating to the invention may contain, in addition to the compounds described above, adjuvants such a halogenating agent, a bleaching agent, a bleach-accelerating agent, an alkaline agent, an acid, an anticorrosion agent and buffering agent. Exemplary examples thereof include ammonium bromide, potassium bromide, imidazole, acetic acid, ammonium nitrate, potassium nitrate, nitric acid, sulfuric acid and ammonia water as well as conventional additives used in bleach-fixing solutions and bleaching solutions.
In commonly used bleach-fixing solutions, a concentrated part containing a bleaching agent such as aminopolycarboxylic acid iron complex salt and a concentrated part containing a thiosulfate are used as plural kit parts in terms of storage stability and physical distribution. The kit part of a bleach-fixing solution relating to the invention is a kit part containing a bleaching agent, referring to a product form when really handed in to users. The kit of a bleaching solution (or bleaching solution kit) relating to the invention may be used as a single kit containing a bleaching agent, a halogenating agent and a buffering agent, or may be separated to plural kit parts, but in either of them, it is a kit containing a bleaching agent, referring to a product form at the time when really handed in to users.